1. Technical Field
The present invention relates in general to an auto enable/disable system and method for computer interfaced devices and in particular to a system and method that automatically communicates to systems and/or persons when a computer interfaced device, such as a serial RAID disk drive, has been enabled or disabled/removed.
2. Description of the Related Art
Some present computer systems have the ability to recognize devices that are added to a bus while the computer is operating, that is, without having to reboot the system. xe2x80x9cPlug and playxe2x80x9d operations allow a computer to configure itself automatically to work with peripherals. The xe2x80x9cplug and playxe2x80x9d operation allows a computer system to recognize a new device that has been added, but the system typically has to be reset in order to properly initialize the added device with the operating system. xe2x80x9cHot plugxe2x80x9d systems and methods were developed as an improvement in this area. In xe2x80x9chot plugxe2x80x9d systems and methods, separate reset lines and other features are provided for each peripheral device, such that a device is able to be initialized with the operating system without requiring the entire system to be rebooted (i.e. xe2x80x9chot-pluggablexe2x80x9d system).
xe2x80x9cHot-pluggablexe2x80x9d devices may be interfaced under various protocols, such as small computer system interface (SCSI), serial storage architecture (SSA), and fiber channel arbitrated loop (FCAL). FIG. 1 shows a SSA example wherein an overall RAID system 10 with target disk drives 12, that is target drives T0, T1, and T2, are serially linked together to a SSA initiator 25. The SSA RAID system 10 is coupled to and communicates with a central processing unit (CPU) 11 and a host computer 16. FIG. 1 shows that the xe2x80x9chot-pluggablexe2x80x9d target disk drives 12 are removable from the overall RAID system 10 and thus unlinked from the host computer 16. Typically, a cam mechanism or carrier lever 14 latches the target disk drive 12 to a disk drive drawer (see FIG. 2). One of the target disk drives 12 is removed from the drawer by unlatching the cam 14, and the serial link or interface is broken when the target disk drive 12 is physically removed from the drawer.
The problem with the breaking of this link is that the host computer 16 has no way of distinguishing that the target disk drive 12 has been removed over actual problems with the target disk drive 12 or software. Therefore, the host computer 16 assumes that a problem with the target disk drive 12 exists even though the target disk drive 12 has been removed, and various extensive routines and troubleshooting and search algorithms are executed to identify and find the problem despite the fact that the target disk drive 12 has been removed. The computer system 16 attempts to talk to the target disk drive 12 to find a problem, such as data error, power loss, or disk drive removal. In other words, when a target disk drive 12 is removed, the computer system 16 cannot distinguish that the back plane connection for that target disk drive 12 and the link 30 from connector 17 to SSA initiator 25 have been broken. The host computer 16 assumes that a problem exists and consumes valuable time, power, and computer resources in attempting to identify the problem and to finally find out that the target disk drive 12 has simply been removed. Therefore, the disadvantage and problem with a removable computer interfaced device is that no system or method exists for communicating to the host computer system the fact that such a device has been removed therefrom.
It would therefore be advantageous and desirable to have a system and method of communicating to the SSA initiator and the host computer when a computer interfaced device has been removed from an overall system. It would be advantageous and desirable to provide an automatic enable and disable system and method when a computer interfaced device has been removed from an overall system. It would also be advantageous and desirable to provide a communications system and method to a host computer and to a SSA initiator when an interfaced device has been unlatched and about to be removed from a system, such as when a xe2x80x9chot-pluggablexe2x80x9d disk drive has been unlatched and about to be removed from a serial RAID system.
It is therefore one object of the present invention to provide a system and method of communicating to an overall system when a computer interfaced device has been unlatched and about to be removed from the overall system.
It is another object of the present invention to provide an automatic enable and disable system and method when a computer interfaced device has been removed from an overall system.
It is a further object of the present invention to provide a communications system and method to a host computer and to a SSA initiator when an interfaced device has been unlatched and about to be removed from the host computer and the SSA initiator, such as when a xe2x80x9chotpluggablexe2x80x9d disk drive has been unlatched and about to be removed from a serial RAID system.
It is still a further object of the present invention to provide a communications system and method that communicates removal of an interfaced device to avoid the execution of various extensive routines and troubleshooting and search algorithms for identifying and finding the problem when the interfaced device, such as a target disk drive, has in fact been removed.
The foregoing objects are achieved as is now described. An automatic enable and disable system and method for a computer interfaced device linkable to an external computer system. Communication occurs when a computer interfaced device has been latched to and inserted into or unlatched and about to be removed from the external computer system. A sensor is coupled to a of the computer interfaced device, and a sensor component is coupled to a cam mechanism or other such component of the computer interfaced device. The sensor component is engagable to and disengagable from the sensor. The sensor senses engaging and disengaging of the sensor component respectively thereto and therefrom as the cam mechanism or such component is latched and unlatched. Latching of the cam mechanism or such component and the computer interfaced device is communicated to the external computer system when the sensor component is engaged to the sensor. Unlatching of the cam mechanism or such component and the fact that the computer interfaced device is about to be removed from the external computer system is communicated to the external computer system when the sensor component is disengaged from the sensor. A non-maskable interrupt is used to couple the sensor to the controller which is in communications with the external computer system. The sensor component is a magnet, light passage blocker, or mechanical sensor component, and the sensor is a hall-effect sensor, an optical sensor, or a mechanical sensor.
The above as well as additional objects, features, and advantages of the present invention will become apparent in the following detailed written description.